Office towers and commercial buildings account for nearly one-fifth of all energy consumed in the United States. Burcin Becerik-­Gerber has found a cheap way to cut a building’s energy use by a third.

Today’s smart buildings can be programmed to default to energy-thrifty measures, such as turning down the heat or air-­conditioning and turning off unnecessary lights—but occupants often just crank everything back up, or even work against the system by plugging in space heaters or opening windows. An assistant professor of civil and environmental engineering at the University of Southern California, Becerik-­Gerber has come up with a way to save energy by essentially getting buildings to “negotiate” with their occupants, factoring in the perceptions and desires of each.

The system uses occupants’ smartphones to open up a line of communication. Becerik-­Gerber worked with colleagues in social psychology and computer science to design an app that asks people how satisfied they are with the work environment’s current temperature, lighting, air quality, and even noise level. System software then fashions each user’s consumption patterns and preferences into a virtual “agent” that resides in his or her smartphone. “The agent works for you and tries to look after you,” she explains.

The system then works with all the building’s agents to find the most energy-efficient way of adjusting the settings so as to make the greatest number of people happy. To improve the results, it asks those users demanding more energy-­intensive conditions if they’d be willing to compromise a bit, and it tells them what the resulting energy savings would be. “If people understand the consequences, they’re more tolerant,” says Becerik-­Gerber. The optimized settings are then put in place and monitored automatically.

Finding an optimal solution for as few as five occupants is difficult. Finding a way to coördinate the preferences of hundreds was massively challenging. The problem is especially acute in today’s popular open-plan offices: people with very different preferences often share space, typically guaranteeing that most of them will be unhappy with the environmental settings. But Becerik-­Gerber’s simulations indicate that her algorithms could satisfy some 70 percent of occupants—while reducing overall energy consumption by more than 30 percent.